With the rapid growth of data services, data transmission pressure on carriers of a licensed frequency spectrum is also increasing. Therefore, using carriers of an unlicensed frequency spectrum to share data traffic on the carriers of the licensed frequency spectrum becomes an important evolution direction of a Long Term Evolution (LTE) system in the future.
In an LTE/LTE-A system, DCI Format 0 and DCI Format 4 may be used for uplink scheduling. Downlink Control Information (DCI) includes scheduling configuration parameters. The scheduling configuration parameters are generally divided into resource configuration parameters and transmission configuration parameters. The resource configuration parameters may be resource block allocation parameters, and the transmission configuration parameters may be a carrier indicator, a format identifier, a Modulation and Coding Scheme (MCS) level, a redundancy version (RV), a New Data Indicator (NDI), a Transmission Power Control (TPC) (TPC) command, etc. In addition, as a trade-off between control signaling overheads and scheduling flexibility, a synchronous adaptive or non-adaptive Hybrid Automatic Repeat Request (HARQ) mechanism is used in the LTE/LTE-A system, and the DCI does not need to include HARQ process numbers. For an asynchronous HARQ mechanism, DCI needs to include the HARQ process numbers of all data packets to distinguish different processes and implement data packet merging.
In a case where an unlicensed frequency spectrum has a low downlink load and a high uplink load, the base station just schedules uplink subframes, and for each uplink subframe, a corresponding downlink subframe is sent, causing a great waste of resources. In a case where a licensed carrier schedules other carriers across carriers, control signaling overheads of the licensed carrier is a bigger trouble. In addition, according to regional regulatory requirements, for uplink data transmission during unlicensed operation of LTE, a User Equipment (UE) needs to perform Listen-Before-Talk (LBT) before scheduling the data transmission in most cases, thus causing a low transmission efficiency of uplink data.
No specific solution has been provided to solve the problem of a reduced uplink data transmission efficiency due to a lack of a technology for reducing signaling overheads and improving an uplink transmission rate on an unlicensed frequency spectrum in the related art.